Hi MrMark,
You're right, the code is almost exactly the same as the current one on my laptop. I'll try to change the buffer to 1000 samples. I agree with you that the results are quite good, but I noticed that you've set the readData function to D4. Wouldn't it be optimized for frequencies from 320 to 350 Hz if you'd choose E1? Asside from that, I believe that with all the help I got from you guys I have a fair change of succeeding in the project 
As for the weird error that I've written about in my previous post, do you have any idea what could be the cause?
Thanks,
Bart